System Explanation
The WNB electrical meter is connected to the high-voltage electrical service to be measured and outputs a contact closure pulse for every unit of energy (eg Watt-hour) that flows through the electrical service. The relationship of pulses and Watt-hours (Wh) depends on the model of WNB meter as well as the full-scale CT’s used. For example, the WNB might be configured to output a pulse for every 100Wh measured.
The WNB requires electrical voltage sensing connections to each of the phases as well as current transformers (CT’s) for current measurement on each of the phase conductors. The power meter runs autonomously sampling the phase voltages and currents very quickly, calculating instantaneous power and totalizing electrical energy (power over time). The WNB then outputs a pulse after a defined amount of energy has been measured. By totalizing these pulses and scaling for the relationship between pulses and energy, the amount of energy measured is known. This scaling and totalization is simply performed by the connected IL-Mini™ data logging instrument.
The WNB meter output is connected via a pair of wires to the digital input channel on the IL-Mini™ which in turn is configured as a Counter input.
IL-Mini™ Programming
To configure the IL-Mini™ for the scaling, counting and other desired data acquisition functions, a program is built within the Logic Beach HyperWare-II software. This program is called a “Program Net” as it consists of a number of icons all visually connected together with a mouse to make a “network”.
The Program Net is then uploaded to the IL-Mini™ memory where it executes. Due to the intuitive flexibility of the HyperWare-II software, there are unlimited data acquisition schemes that can be implemented with the Program Net. Below is a simple Program Net that samples reads the accumulated pulse totals received on the Counter input every 5 minutes, converts the pulses to kWh then sums them for 15 minute and 24 hour intervals and stores the totals to memory accordingly.
System Components Used
| Part Number | Description | Qty | Comment |
|---|---|---|---|
| IL-Mini-Dbatt | IntelliLogger IL-Mini™ with the D-cell battery pack option. | 1 | Battery pack is specified such that installation is simplified and the unit will run unattended for months if desired. |
| 3539.22000 | IL-Mini™ Surface or wall mounting bracket | 1 | If desired |
| WNB-3Y-208-P | Electrical Meter; pulse output for 120/240Vac service with neutral | 1 | Other Electrical Meter models are available for different electrical service configurations. |
| CTS-750-100 | Split-Core Curernt Transformer. 0.75” aperture (opening), 100Aac full scale. | 2 | CT’s with other apertures and full scale current ratings are available |
| HW2M | HyperWare-II for IL-Mini™ Single User License | 1 | If not already owned. |
| USB Cable | USB Cable; Type A to Mini-B | 1 | If not already owned. This is a common cable used with cameras and other USB devices |
Other System Considerations. . .
Unused Analog Input Channels
In this configuration, the IL-Mini™ has four unused analog inputs. These inputs can readily be utilized for temperature, pressure, flow, or other inputs from various analog transducers and sensors.
Poly-Phase Applications
For 3-phase applications, the WNB meter can be equipped with an additional CT and voltage sense input.
Monitoring Multiple Services Simultaneously; Method 1:
Utilize the IntelliLogger IL-10, IL-20, IL-80 or IL-90. Each of these models have four or more Counter inputs. The IL-90 can monitor up to 16 pulse output meters simultaneously.
Monitoring Multiple Services Simultaneously; Method 2:
The IL-Mini™ can be provided with a Modbus RTU option. This allows the IL-Mini™ to communicate serially with one or more Modbus enabled power meters (WNC model) on a single Modbus RS-485 network.